Acoustic and Fiber Optic Network for Use in Laterals Downhole

ABSTRACT

Communication between a lateral and a main bore is established wirelessly preferably using sensors that transmit sensed parameters in the lateral and transmit acoustically coded messages to the main bore preferably into a fiber optic cable that extends in the main bore. The sensors have stored or/and generated power and communicate from their location to the fiber optic cable in the main bore either directly or indirectly using a network of sensors to relay the information along the lateral to the fiber optic. A surface processor can then associate the data from specific sensors and alternatively communicate with certain sensors to start or stop transmitting data.

FIELD OF THE INVENTION

The field of this invention is communication of information between a lateral in a wellbore and the surface through a main bore.

BACKGROUND OF THE INVENTION

Lateral wellbores are frequently made by using a whipstock to redirect a bit to come through a casing wall and then continuing to drill and later complete one or more laterals. The mill or drill makes an elongated opening in the casing wall of the main bore through which production tubing is extended after the lateral is completed. Efforts to gather data from a lateral to the surface have frequently involved a continuous communication conduit as an auxiliary conduit to the production tubing and usually connected to the outside of the production tubing and extending from the lateral to the surface. The problem with this approach regardless of the nature of the information conduit from the lateral to the surface is that the conduit has to go through the elongated window that was originally made to drill the lateral. This window can have sharp edges or provide a pinch point where damage to the communication conduit can occur during installation or perhaps during subsequent production operations. Some illustrations of hard wire systems into laterals for communication are illustrated in U.S. Pat. Nos. 6,776,636; 6,318,457; 6,902,414 and 7,165,618. WO 2005/124397 illustrates the use of transducers to transmit an acoustic signal across threaded connections.

Main bores of wells with laterals frequently have a communication conduit from the surface that extends to the producing zone for gathering data on well conditions and for transmission of power to downhole equipment. One type of such conduit is a fiber optic cable. The present invention seeks to provide communication from a lateral to a main bore and preferably to a communication conduit in the main bore such as a fiber optic. The lateral can feature sensors and transmitters such as acoustic transmitters that are preferably coupled with power supplies or an ability to generate power to send a coded signal from the lateral to the main bore without a hard wire going into the window for the lateral. The signals can go directly from the sensor to the main bore or can be relayed through a network of sensors to the main bore to preserve signal strength and clarity such as by using sensors as repeaters in an array that extends to provide the desired coverage in the lateral. These and other aspects of the present invention will be more apparent to those skilled in the art from a review of the description of the preferred embodiment and the associated drawings while recognizing that the claims describe the full scope of the invention.

SUMMARY OF THE INVENTION

Communication between a lateral and a main bore is established wirelessly preferably using sensors that transmit sensed parameters in the lateral and transmit acoustically coded messages to the main bore preferably into a fiber optic cable that extends in the main bore. The sensors have stored or/and generated power and communicate from their location to the fiber optic cable in the main bore either directly or indirectly using a network of sensors to relay the information along the lateral to the fiber optic. A surface processor can then associate the data from specific sensors and alternatively communicate with certain sensors to start or stop transmitting data.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a main wellbore and a lateral showing the array of sensors that can communicate with a fiber optic conduit in the main wellbore;

FIG. 2 is a detailed view of a sensor assembly illustrating schematically the power supply and generation components of the assembly.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 shows a wellbore 10 with a lateral 12 and a string 14 running into the lateral 12. The main bore 16 is closed with a packer 18. A conduit 20 which preferably is a fiber optic that had been used for data transmission between downhole and the surface is still in place in main bore 16. Conduit 20 can be a single line or a unshaped line that goes down and comes back up to the surface. Fasteners 21 can secure the conduit to the string 14 in a manner where the conduit 20 does not continue into the lateral 12 or the conduit 20 can be one that remained in place before the string 14 was run into the well. Those skilled in the art will appreciate that the main could still be open or producing and is just used for illustrative purposes. The conduit 20 could be in a lateral off an original bore wherein from the lateral there have been other laterals drilled. The concept is as broad as delivering information from a branch to an adjacent bore from where the branch started without hard wiring a conduit for information or power delivery through the window for the lateral.

The conduit 20 does not run into the lateral 12. In the lateral 12 and supported by conduit 14 are an array of sensors 22 that can monitor different downhole conditions such as temperature, pressure, pH, water or other conditions downhole that are used to determine how the well will be produced. The sensors 22 need not all be unique as far as the measured variable. Redundancy is also possible so that if a given sensor has operational difficulties or a loss of power for example, there are other sensors positioned sufficiently close to act as a backup to transmit data. Alternatively, the sensors 22 can relay information to each other in a direction toward conduit 20 to keep the data in a recognizable format when it is transmitted to the conduit 20 where it engages the string 14 in main bore 10. In essence the initial transmitted signal is repeated to a closer sensor that is capable of receiving and repeating a signal until it reaches the conduit 20. While the drawing indicates conduit 20 as separated from string 14 for clarity, they can be in contact when for example the sensors convey information acoustically into the string 14 and that information is transmitted into conduit 20 to go to the surface. At the surface, the signals that originate from any given sensor can be identified as part of the transmitted signal from any sensor 22 is encoded to identify its location and orientation on string 14.

FIG. 2 illustrates the details of a particular sensor 22. The first layer 24 comprises the actual sensor components for sensing the measure variable and sending out, in the preferred embodiment a coded signal that directly or indirectly moves through the lateral 12 to reach the conduit 20 and then on to the surface for processing. Layer 26 is the power supply which can be a rechargeable battery. The assembly is completed with a damper layer 28 between the battery 26 and the power generation layer 30. The power generation layer can employ piezoceramic technology to generate power. An electric line or wireline supporting a sonde 32 can be run in through the string 14 to make electrical contact with a battery 26 on a particular sensor 22 and recharge the battery that may have discharged. Each sensor can be powered on or off with the sonde, shown schematically as 32 in FIG. 1. Those skilled in the art will recognize that sonde 32 is deployed on wireline or electric line through the string 14 to make selective electrical contact with one or more sensors 22 and/or switch them on line or off line. While acoustic signals are preferred from sensors 22 use of electromagnetic signals is an alternative.

The above description is illustrative of the preferred embodiment and many modifications may be made by those skilled in the art without departing from the invention whose scope is to be determined from the literal and equivalent scope of the claims below: 

1. A method for monitoring at least one well condition in a lateral extending from a wellbore: placing at least one sensor on a string extending from the main bore and into the lateral; transmitting a signal of a sensed variable in the lateral from said sensor and into said main bore without a hard wired connection.
 2. The method of claim 1, comprising: transmitting the signal received in the main bore to the surface on a conduit.
 3. The method of claim 2, comprising: providing a fiber optic cable as said conduit.
 4. The method of claim 3, comprising: transmitting an acoustic or electromagnetic signal from said sensor.
 5. The method of claim 4, comprising: providing a plurality of sensors as said at least one sensor; relaying a given signal from one sensor to at least one other sensor in the lateral before the signal reaches the main bore.
 6. The method of claim 5, comprising: providing a power generating capability with at least one of said sensors.
 7. The method of claim 6, comprising: providing a power storage capability with at least one of said sensors.
 8. The method of claim 7, comprising: charging said power storage device through said string.
 9. The method of claim 7, comprising: providing redundant sensors to measure the same variable; switching, via said string, power on to one sensor after power at another sensor sensing the same variable has stopped transmitting.
 10. The method of claim 4, comprising: coding a signal from a given sensor so that its location can be identified with a surface processor.
 11. The method of claim 8, comprising: delivering a sonde into said string to perform said charging.
 12. The method of claim 6, comprising: using a piezoceramic power generator with said power storage capability.
 13. The method of claim 1, comprising: receiving said signal in said main bore with a fiber optic cable.
 14. The method of claim 1, comprising: transmitting an acoustic or electromagnetic signal from said sensor.
 15. The method of claim 1, comprising: providing a plurality of sensors as said at least one sensor; relaying a given signal from one sensor to at least one other sensor in the lateral before the signal reaches the main bore.
 16. The method of claim 1, comprising: providing a power generating capability with at least one of said sensors.
 17. The method of claim 16, comprising: providing a power storage capability with at least one of said sensors.
 18. The method of claim 17, comprising: charging said power storage device through said string.
 19. The method of claim 1, comprising: providing redundant sensors to measure the same variable; switching, via said string, power on to one sensor after power at another sensor sensing the same variable has stopped transmitting.
 20. The method of claim 1, comprising: coding a signal from a given sensor so that its location can be identified with a surface processor. 